1. Technical Field
The invention relates to the field of power supplies for image viewing devices, and more particularly to an improved battery and external power supply pack for a helmet mounted night viewer.
2. Background Art
Image viewing devices, such as image intensifier night vision goggles, are used generally by members of the military as well as others for detecting or sensing images of a scene. Such image viewers typically require a power source to provide power for the included electrical circuitry. For certain types of image viewers, such as an ANVIS type of night vision goggle that is attached to the front of an aviator""s helmet, SPH-4 for instance, it is preferred that the power supply or source be remotely mounted from the image viewer. Remotely mounting the comparatively heavy power supply somewhat relieves tension on the neck of the operator. Known types of separate power sources are disclosed in U.S. Pat. Nos. 5,683,831 and 6,081,094, for example.
However, such a known reduced size or compact battery pack has not included a provision for power from the external aircraft power sources. There are numerous reasons for this nonuse of the aircraft power supply, such as the reduction of weight and size savings.
While the above cited references introduce and disclose a number of noteworthy advances and technological improvements within the art, none completely fulfills the specific objectives achieved by this invention.
In accordance with the present invention, a transportable power source for an image viewing type device includes a battery pack housing assembly to internally hold a first battery pack. An electrical interface circuit receives an input voltage level and provides a resulting output voltage level as an output therefrom to operate the viewer device. The electrical interface circuit is adapted to receive a selected first input voltage level from the first battery pack. The electrical interface circuit is adapted to receive a selected second input voltage level from a power supply source external to the battery pack housing. The electrical interface circuit further includes a switch for selecting between sources of input voltage levels from among at least the first input voltage level from the battery pack and the second input voltage level from the power supply source that is external to the battery pack housing assembly. The switch also is used to selectively control the source for the resulting output voltage level from the battery pack housing assembly.
Preferably, the battery pack housing assembly is adapted to conform to an exterior surface of the helmet, such as a military aviator""s or other ballistic impact protection types of helmets. A support may also be included for attaching the battery pack housing assembly to the exterior surface of the helmet.
These and other objects, advantages and features of this invention will be apparent from the following description taken with reference to the accompanying drawings, wherein is shown the preferred embodiments of the invention.